Home I got the iPhone 3gs and its version is 3 0 but now its upgrade to 3 1 is avalible in itunes and its dedicate to upgrade using itunes the problem is that i afraid that upgrade using itunes may harm

I got the iPhone 3gs and its version is 3 0 but now its upgrade to 3 1 is avalible in itunes and its dedicate to upgrade using itunes the problem is that i afraid that upgrade using itunes may harm?